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Slow wave A new study reveals how death in organisms, including humans, spreads like a wave from cell to cell until the whole individual is dead.

The good news is that, in certain cases, scientists may be able to stop the biochemical process that leads to this death wave, reviving the individual.

It's difficult to study such life and death matters on animals. Who would want to volunteer for a study that ended in death? So researchers instead focused their analysis on worms, which surprisingly possess mechanisms that are similar to those that are active in mammals.

A remarkable feature of worms is that, as they die, the spread of death through their bodies can easily be seen under magnification. It's a fluorescent blue light caused by necrosis, or the cell death pathway. This, in turn, is dependent upon calcium signalling.

The source of the blue hue is a molecule called anthranillic acid.

"We've identified a chemical pathway of self-destruction that propagates cell death in worms, which we see as this glowing blue fluorescence travelling through the body," says David Gems from the Institute of Health Aging at University College London, who led the study.

"It's like a blue grim reaper, tracking death as it spreads throughout the organism until all life is extinguished."

Triggered breakdown

As a hypothetical, let's say a worm or a person is stuck in the desert, suffering from severe dehydration. The stress and strain of that leads to cellular shock and damage, causing individual cells to die.

The entire organism doesn't just die in an instant. The individual cell deaths trigger a chemical reaction that leads to the breakdown of cell components and a build-up of molecular debris. If this goes on unchecked, the individual is toast.

This type of damage can happen, but in a much slower way, as an individual ages.

Scientists cannot revive every single cell in a body, once it's aged out of commission.

But if the worm study is any indication, researchers might be able to stop the calcium signalling biochemical spread of death under other non-aging-related circumstances.

"We found that when we blocked this pathway, we could delay death induced by a stress such as infection, but we couldn't slow death from old age," says Gems. "This suggests that aging causes death by a number of processes acting in parallel."

He says that "the findings cast doubt on the theory that aging is simply a consequence of an accumulation of molecular damage. We need to focus on the biological events that occur during ageing and death to properly understand how we might be able to interrupt these processes."